Because the winding spring of a vehicle seat belt retractor can exert a bothersome pressure of the belt against the chest and waist of the vehicle occupant, vehicles are often equipped with seat belt retractors having a winding mechanism in which the belt tension can be reduced or entirely eliminated when the belt is done up. In several previously known designs of windings mechanisms with tension-reduction or tension-elimination features, the occupant pulls the belt out from the retractor, does up the buckle, allows the belt to wind partly back onto the retractor to take up the slack and then pulls the belt out a small amount to place the winding mechanism in the tension-reduced or tensionless mode. There is no problem with these types of retractor if the occupant uses them properly. Some people, however, do not allow the slack to be taken up fully, or they may be leaning forward when they allow the belt to rewind. In these cases, a tensionless retractor allows the belt to remain slackened, and the vehicle occupant is not well protected in case of an accident. With a tension-reduction type of retractor winding mechanism, the force of the auxiliary spring acting on the belt in the tension-reduced mode may not be great enough to take up the slack, especially if the occupant leaves a large amount of slack in the belt when activating the tension-reducing mechanism. Again, the protection of the occupant is diminished.